Thomas Barrett 5c0b66529a arch: x86_64: handle npot CPU topology ... This PR addresses a bug in which the cpu topology of a guest with non power-of-two number of cores is incorrect. For example, in some contexts, a virtual machine with 2-sockets and 12-cores will incorrectly believe that 16 cores are on socket 1 and 8 cores are on socket 2. In other cases, common topology enumeration software such as hwloc will crash. The root of the problem was the way that cloud-hypervisor generates apic_id. On x86_64, the (x2) apic_id embeds information about cpu topology. The cpuid instruction is primarily used to discover the number of sockets, dies, cores, threads, etc. Using this information, the (x2) apic_id is masked to determine which {core, die, socket} the cpu is on. When the cpu topology is not a power of two (e.g. a 12-core machine), this requires non-contiguous (x2) apic_id. Signed-off-by: Thomas Barrett <tbarrett@crusoeenergy.com>		2024-01-01 10:05:03 +00:00
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integration.rs	arch: x86_64: handle npot CPU topology	2024-01-01 10:05:03 +00:00